blob: e85f856b859219b1987dda9a403e07f4ded45769 [file] [log] [blame]
Heikki Krogeruse2d0e902014-05-15 16:40:25 +03001/*
2 * Copyright (C) 2014 Intel Corporation
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * Adjustable fractional divider clock implementation.
9 * Output rate = (m / n) * parent_rate.
10 */
11
12#include <linux/clk-provider.h>
13#include <linux/module.h>
14#include <linux/device.h>
15#include <linux/slab.h>
16#include <linux/gcd.h>
17
18#define to_clk_fd(_hw) container_of(_hw, struct clk_fractional_divider, hw)
19
20static unsigned long clk_fd_recalc_rate(struct clk_hw *hw,
21 unsigned long parent_rate)
22{
23 struct clk_fractional_divider *fd = to_clk_fd(hw);
24 unsigned long flags = 0;
25 u32 val, m, n;
26 u64 ret;
27
28 if (fd->lock)
29 spin_lock_irqsave(fd->lock, flags);
Stephen Boyd661e2182015-07-24 12:21:12 -070030 else
31 __acquire(fd->lock);
Heikki Krogeruse2d0e902014-05-15 16:40:25 +030032
33 val = clk_readl(fd->reg);
34
35 if (fd->lock)
36 spin_unlock_irqrestore(fd->lock, flags);
Stephen Boyd661e2182015-07-24 12:21:12 -070037 else
38 __release(fd->lock);
Heikki Krogeruse2d0e902014-05-15 16:40:25 +030039
40 m = (val & fd->mmask) >> fd->mshift;
41 n = (val & fd->nmask) >> fd->nshift;
42
Heikki Krogerus6b547832015-02-02 15:37:04 +020043 if (!n || !m)
44 return parent_rate;
45
Heiko Stübnerfeaefa02014-08-28 12:46:10 +020046 ret = (u64)parent_rate * m;
Heikki Krogeruse2d0e902014-05-15 16:40:25 +030047 do_div(ret, n);
48
49 return ret;
50}
51
52static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate,
53 unsigned long *prate)
54{
55 struct clk_fractional_divider *fd = to_clk_fd(hw);
56 unsigned maxn = (fd->nmask >> fd->nshift) + 1;
57 unsigned div;
58
59 if (!rate || rate >= *prate)
60 return *prate;
61
62 div = gcd(*prate, rate);
63
64 while ((*prate / div) > maxn) {
65 div <<= 1;
66 rate <<= 1;
67 }
68
69 return rate;
70}
71
72static int clk_fd_set_rate(struct clk_hw *hw, unsigned long rate,
73 unsigned long parent_rate)
74{
75 struct clk_fractional_divider *fd = to_clk_fd(hw);
76 unsigned long flags = 0;
77 unsigned long div;
78 unsigned n, m;
79 u32 val;
80
81 div = gcd(parent_rate, rate);
82 m = rate / div;
83 n = parent_rate / div;
84
85 if (fd->lock)
86 spin_lock_irqsave(fd->lock, flags);
Stephen Boyd661e2182015-07-24 12:21:12 -070087 else
88 __acquire(fd->lock);
Heikki Krogeruse2d0e902014-05-15 16:40:25 +030089
90 val = clk_readl(fd->reg);
91 val &= ~(fd->mmask | fd->nmask);
92 val |= (m << fd->mshift) | (n << fd->nshift);
93 clk_writel(val, fd->reg);
94
95 if (fd->lock)
96 spin_unlock_irqrestore(fd->lock, flags);
Stephen Boyd661e2182015-07-24 12:21:12 -070097 else
98 __release(fd->lock);
Heikki Krogeruse2d0e902014-05-15 16:40:25 +030099
100 return 0;
101}
102
103const struct clk_ops clk_fractional_divider_ops = {
104 .recalc_rate = clk_fd_recalc_rate,
105 .round_rate = clk_fd_round_rate,
106 .set_rate = clk_fd_set_rate,
107};
108EXPORT_SYMBOL_GPL(clk_fractional_divider_ops);
109
110struct clk *clk_register_fractional_divider(struct device *dev,
111 const char *name, const char *parent_name, unsigned long flags,
112 void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth,
113 u8 clk_divider_flags, spinlock_t *lock)
114{
115 struct clk_fractional_divider *fd;
116 struct clk_init_data init;
117 struct clk *clk;
118
119 fd = kzalloc(sizeof(*fd), GFP_KERNEL);
Stephen Boydd122db72015-05-14 16:47:10 -0700120 if (!fd)
Heikki Krogeruse2d0e902014-05-15 16:40:25 +0300121 return ERR_PTR(-ENOMEM);
Heikki Krogeruse2d0e902014-05-15 16:40:25 +0300122
123 init.name = name;
124 init.ops = &clk_fractional_divider_ops;
125 init.flags = flags | CLK_IS_BASIC;
126 init.parent_names = parent_name ? &parent_name : NULL;
127 init.num_parents = parent_name ? 1 : 0;
128
129 fd->reg = reg;
130 fd->mshift = mshift;
131 fd->mmask = (BIT(mwidth) - 1) << mshift;
132 fd->nshift = nshift;
133 fd->nmask = (BIT(nwidth) - 1) << nshift;
134 fd->flags = clk_divider_flags;
135 fd->lock = lock;
136 fd->hw.init = &init;
137
138 clk = clk_register(dev, &fd->hw);
139 if (IS_ERR(clk))
140 kfree(fd);
141
142 return clk;
143}
144EXPORT_SYMBOL_GPL(clk_register_fractional_divider);